Fair Value of Financial Instruments (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Carrying Value [Member]
Derivative [Line Items]
Notes and bonds payable	[1]	$ 1,381.3	$ 1,403.7
Mortgage notes receivable	[1]	0.0	1.9
Fair Value [Member]
Derivative [Line Items]
Notes and bonds payable	[1]	1,396.5	1,438.8
Mortgage notes receivable	[1]	$ 0.0	$ 1.9

[1] Level 3 - Fair value derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable.